Shoes having a shock-absorbing function and a breathing function are known as disclosed, for example, in Japanese Patent (JP-B1) No. 3011408.
The disclosed shoe has a sole member formed with a recessed portion opening toward an internal space of the shoe, and an elastic member fitted in the recessed portion. The elastic member has shock-absorbing ability and breathability. More specifically, the elastic member comprises an elastic case having a plurality of airflow holes or orifices formed therein, and a large number of elastic particles packed in layers within the case. The recessed portion is formed in a ball portion and a heel portion of the sole member, which respectively correspond in position to a ball and a heel of the wearer's foot. The elastic particles are formed from spheres or balls of elastic rubber. In one preferred embodiment, the rubber balls have a diameter of 5 mm and a hardness of Hs 40.
By virtue of the elastic members placed in the ball and heel portions of the sole member with the elastic balls packed in layers therein, the shoe can offer a good shock-absorbing capability in which the elastic balls absorb shocks during walking. At the same time, by virtue of the airflow orifices formed in each elastic case filled with the elastic balls, the shoe can also offer a breathing capability in which a promoted breathing action (or airflow inside the shoe) takes place upon repeated compression and recovery of the shape of individual elastic balls.
However, due to the elastic members embedded in the ball and heel portions of the sole member, the conventional shoe requires a considerably large amount of elastic balls for forming such elastic members. Furthermore, since the elastic balls are packed in layers, functionality-focused designing of the shoes will render the elastic members large in thickness. The thick elastic members are disadvantageous particularly when they are incorporated in a sole insert because the sole insert itself becomes thick and hence is less fashionable and defective from an aesthetic viewpoint. Additionally, since the elastic balls packed in layers within the elastic case can flow or move either within the same ball layer or between adjacent ball layers during use, foot comfort of the conventional shoe is not fully satisfactory.
Due to the difficulties discussed above, the conventional shoe is not suitable for applications where a sole insert is not used or the fashionability or aesthetic appearance is a major requirement such as experienced in the case of women's shoes including pumps, mules, sandals or the like.
Shoes having a shock-absorbing function have found an increasing demand regardless of whether the shoes are used for athletic or walking purposes, or for business purposes. Even in the case of women's shoes, such as pumps, mules or sandals, which are generally used without a sole insert, the shock-absorbing function is desirable to the extent that the fashionability or aesthetic appearance of the shoes is not deteriorated.